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  • Will this LINQ-TO-SQL query fetch all records from the table ?

    - by Puneet Dudeja
    public long GetNewCRN() { return ((from c in DataContext.GetTable<Cust_Master>() select c.CUSTSERH_CRN).Max() + 1); } Will this Linq to Sql query fetch all records from the table first and then select the maximum of the column ? If yes, then isn't it a bad idea using linq to sql instead of normal SqlCommand ? Or is there any other way of doing it in linq to sql ? When I attach Console.Out, I see nothing(command prompt does not even open). But when I include following:- context.Log = new System.IO.StreamWriter("d:\\abcd.txt"); I get an error, that "The process can not access the file because it is being used by another process" and that process is "w3wp.exe". How can I see the sql commands being executed by DataContext then ?

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  • when i merge a data table with a typed dataset, one single field on a single row is DBNull sometimes

    - by benj007
    Hi everybody, I have a strange problem sometimes when I try to merge a data table with a typed dataset my data table is filled in with a stored procedure and when I checked the content of this table it is ok, everything is in there straight after I merge it with my core typed dataset like this : MyTypedDataSet.TheTable.Clear(); MyTypedDataSet.TheTable.Merge(MyDataTable); and now if i check the table in the dataset everything is ok except only one single field on one single row which is DBNull, that makes no sense because the source data table contains the good integer vaue. Thanks a lot in advance guys :)

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  • Why do SQL connection leave parameters in?

    - by acidzombie24
    While coding with sqlite everytime i always had the exact number of parameters and when i executed the query i always had 0 parameters after it. I kept using the cmd object and it worked fine. Now while porting to use sql server (2008) my SqlConnection has parameters left over from a successful command. Why? I seem to be able to create tables without the problem (then again i may have use a clone of an empty cmd since i use recursion). Does SqlCommand always leave the parameters in after a query? This always breaks the following query unless i do parameter.clear(). Should i create a new SqlCommand object? or use parameter.clear() each time? I'm somewhat confused.

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  • Accessing MS Access database from C#

    - by Abilash
    I want to use MS Access as database for my C# windows form application.I have used OleDb driver for connecting MS Access. I am able to select the records from the MS Access using OleDbConnection and ExecuteReader.But I am un able to insert,update and delete records. My code is as follows: OleDbConnection con=new OleDbConnection(strCon); try { con.Open(); OleDbCommand com = new OleDbCommand("INSERT INTO DPMaster(DPID,DPName,ClientID,ClientName) VALUES('53','we','41','aw')", con); int a=com.ExecuteNonQuery(); //OleDbCommand com = new OleDbCommand("SELECT * FROM DPMaster", con); //OleDbDataReader dr = com.ExecuteReader(); //while (dr.Read()) //{ // MessageBox.Show(dr[2].ToString()); //} MessageBox.Show(a.ToString()); } catch { MessageBox.Show("cannot"); } If I execute the commented block the application works.But the insert block doesnt works.Why I am unable to insert/update/delete the records into database? My Connection String is as follows: string strCon="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=xyz.mdb;Persist Security Info=True";

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  • DBTransactions between stateless calls using GUIDs

    - by Marty Trenouth
    I'm looking to add transactional support to my DB engine and providing to Abstract Transaction Handling down to passing in Guids with the DB Action Command. The DB engine would run similar to: private static Database DB; public static Dictionary<Guid,DBTransaction> Transactions = new ...() public static void DoDBAction(string cmdstring,List<Parameter> parameters,Guid TransactionGuid) { DBCommand cmd = BuildCommand(cmdstring,parameters); if(Transactions.ContainsKey(TransactionGuid)) cmd.Transaction = Transactions[TransactionGuid]; DB.ExecuteScalar(cmd); } public static BuildCommand(string cmd, List<Parameter> parameters) { // Create DB command from EntLib Database and assign parameters } public static Guid BeginTransaction() { // creates new Transaction adding it to "Transactions" and opens a new connection } public static Guid Commit(Guid g) { // Commits Transaction and removes it from "Transactions" and closes connection } public static Guid Rollback(Guid g) { // Rolls back Transaction and removes it from "Transactions" and closes connection } The Calling system would run similar to: Guid g try { g = DBEngine.BeginTransaction() DBEngine.DoDBAction(cmdstring1, parameters,g) // do some other stuff DBEngine.DoDBAction(cmdstring2, parameters2,g) // sit here and wait for a response from other item DBEngine.DoDBAction(cmdstring3, parameters3,g) DBEngine.Commit(g) } catch(Exception){ DBEngine.Rollback(g);} Does this interfere with .NET connection pooling (other than a connection be accidently left open)? Will EntLib keep the connection open until the commit or rollback?

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  • Sort a GridView Column related to other Table

    - by Tim
    Hello, i have a GridView bound to a DataView. Some columns in the DataView's table are foreignkeys to related tables(f.e. Customer). I want to enable sorting for these columns too, but all i can do is sorting the foreignkey(fiCustomer) and not the CustomerName. I have tried this without success(" Cannot find column ERP_Customer.CustomerName "): <asp:TemplateField HeaderText="Customer" SortExpression="ERP_Customer.CustomerName" > A tried also the DataViewManager, but i've a problem to detect the table to sort: Dim viewManager As New DataViewManager(Me.dsERP) viewManager.DataViewSettings(dsERP.ERP_Charge).RowFilter = filter viewManager.DataViewSettings(dsERP.ERP_Charge).Sort = sort 'sort is the GridView's SortExpression Me.GrdCharge.DataSource = viewManager.CreateDataView(dsERP.ERP_Charge) I have to apply the sort on a distinct table of the DataViewManager, but this table would differ on the related tables. I have bound the TemplateColumns in Codebehind in RowDataBound-Event f.e.: Dim LblCustomer As Label = DirectCast(e.Row.FindControl("LblCustomer"), Label) LblCustomer.Text = drCharge.ERP_CustomerRow.CustomerName 'drCharge inherits DataRow What is the recommended way to sort a GridView on columns related to another table?

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  • Letting Wcf data service implement another contract

    - by Wasim
    Hi all , I have a wcf data service with the standart configuration . I want to add another functionality to it , so I built a contract interface and let my wcf data service implements it . Now I see in the service the InitializeService method , and the contract interface methods . When I come to connect the service , I get an error , that there is no end point declared to the contract I added . How can do that ? examples ? links ? I choosed to add the contract interface to the wcf data service and not adding another service , because the client application uses the wcf data service generated objects , and I want to use the same obkject to make operations not related to data , for more coplex processing . If I do the methods in another service , then I have types incompatibility . Thanks in advance ...

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  • im unable to validate a login of users ,since if im entering the wrong values my datareader is not getting executed y ?

    - by Salman_Khan
    //code private void glassButton1_Click(object sender, EventArgs e) { if (textBox1.Text == "" || textBox1.Text == "" || comboBox1.SelectedIndex == 0) { Message m = new Message(); m.ShowDialog(); } else { try { con.ConnectionString = "Data source=BLACK-PEARL;Initial Catalog=LIFELINE ;User id =sa; password=143"; con.Open(); SqlCommand cmd = new SqlCommand("Select LoginID,Password,Department from Login where LoginID=@loginID and Password=@Password and Department=@Department", con); cmd.Parameters.Add(new SqlParameter("@loginID", textBox1.Text)); cmd.Parameters.Add(new SqlParameter("@Password", textBox2.Text)); cmd.Parameters.Add(new SqlParameter("@Department", comboBox1.Text)); SqlDataReader dr = cmd.ExecuteReader(); if (dr.Read()) { string Strname = dr[0].ToString(); string StrPass = dr[1].ToString(); string StrDept = dr[2].ToString(); if(dr[2].ToString().Equals(comboBox1.Text)&&dr[0].ToString().Equals(textBox1.Text)&&dr[1].ToString().Equals(textBox2.Text)) { MessageBox.Show("Welcome"); } else { MessageBox.Show("Please Enter correct details"); } } dr.Close(); } catch (Exception ex) { MessageBox.Show("Exception" + ex); } finally { con.Close(); } } }

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  • Can I call DbDataAdapter.Fill with a DbDataAdapter.SelectCommand that has a inner join to populate

    - by matti
    or do I have to use 2 separate DbDataAdapters with single-table Selects and then use DataRelations? like: SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo FROM Persons INNER JOIN Orders ON Persons.P_Id=Orders.P_Id ORDER BY Persons.LastName I can't yet try this. I'm designing a xml config file schema for a general program so it would help a lot! -cheers & BR: Matti

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  • Faster way to update 250k rows with SQL

    - by pablo
    I need to update about 250k rows on a table and each field to update will have a different value depending on the row itself (not calculated based on the row id or the key but externally). I tried with a parametrized query but it turns out to be slow (I still can try with a table-value parameter, SqlDbType.Structured, in SQL Server 2008, but I'd like to have a general way to do it on several databases including MySql, Oracle and Firebird). Making a huge concat of individual updates is also slow. What about creating a temp table and running an update joining my table and the tmp one? Will it work faster?

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  • How to return table name from stored procedure in dataset.

    - by Shantanu Gupta
    I used a dataset to store 15 tables that I need at the time of loading. When i filled all the tables using stored procedure it returns me all the table but name of the table doesn't comes as that of actual table name in a database. It takes all the table with table name as Table1, Table2, Table3... I want them to be with the name as they actually are in table. SELECT PK_GUEST_TYPE, [DESCRIPTION] FROM L_GUEST_TYPE SELECT PK_AGE_GROUP_ID, AGE_GROUP FROM L_AGE_GROUP SELECT PK_COMPANY_ID, COMPANY_NAME FROM M_COMPANY SELECT PK_COUNTRY_ID, COUNTRY FROM L_COUNTRY SELECT PK_EYE_COLOR_ID, [DESCRIPTION] FROM L_EYE_COLOR SELECT PK_GENDER_ID, [DESCRIPTION] FROM L_GENDER SELECT PK_HAIR_COLOR_ID, [DESCRIPTION] FROM L_HAIR_COLOR SELECT PK_STATE_PROVONCE_ID, [DESCRIPTION] FROM L_STATE_PROVINCE SELECT PK_STATUS_ID, [DESCRIPTION] FROM L_STATUS SELECT PK_TITLE_ID, [DESCRIPTION] FROM L_TITLE SELECT PK_TOWER_ID, [DESCRIPTION] FROM M_TOWER SELECT PK_CITY_ID, [DESCRIPTION] FROM L_CITY SELECT PK_REGISTER_TYPE_ID, [DESCRIPTION] FROM L_REGISTER_TYPE Here is my frontend coding to fill dataset. OpenConnection(); adp.Fill(ds); CloseConnection(true);

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  • What's the most DRY-appropriate way to execute an SQL command?

    - by Sean U
    I'm looking to figure out the best way to execute a database query using the least amount of boilerplate code. The method suggested in the SqlCommand documentation: private static void ReadOrderData(string connectionString) { string queryString = "SELECT OrderID, CustomerID FROM dbo.Orders;"; using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand command = new SqlCommand(queryString, connection); connection.Open(); SqlDataReader reader = command.ExecuteReader(); try { while (reader.Read()) { Console.WriteLine(String.Format("{0}, {1}", reader[0], reader[1])); } } finally { reader.Close(); } } } mostly consists of code that would have to be repeated in every method that interacts with the database. I'm already in the habit of factoring out the establishment of a connection, which would yield code more like the following. (I'm also modifying it so that it returns data, in order to make the example a bit less trivial.) private SQLConnection CreateConnection() { var connection = new SqlConnection(_connectionString); connection.Open(); return connection; } private List<int> ReadOrderData() { using(var connection = CreateConnection()) using(var command = connection.CreateCommand()) { command.CommandText = "SELECT OrderID FROM dbo.Orders;"; using(var reader = command.ExecuteReader()) { var results = new List<int>(); while(reader.Read()) results.Add(reader.GetInt32(0)); return results; } } } That's an improvement, but there's still enough boilerplate to nag at me. Can this be reduced further? In particular, I'd like to do something about the first two lines of the procedure. I don't feel like the method should be in charge of creating the SqlCommand. It's a tiny piece of repetition as it is in the example, but it seems to grow if transactions are being managed manually or timeouts are being altered or anything like that.

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  • Getting row right after insert returns no result

    - by Peekyou
    I am running unit tests and when I try to insert data in the database and getting it right after, I don't get anything (I have tried with DataAdapter and DataReader). However when I put a 3 seconds sleep (even with 1 second it doesn't work...) between the insert and the select I get the result. In SQL Server Profiler I can see the execution, the insert is well done and is completed about 10 miliseconds before the select begins. I can't find out where this comes

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  • What is a 'better' approach to query/save from server: DTO or Wcf Data Services?

    - by bonefisher
    From my perspective, the Data Services and their query approach is useful when querying simple object graphs from your server-side domain model. But when you want to query complex dependencies I couldn't create anything good out of it. The classic DTO approach is fine-grained and can handle everything, but the downside is that you have to create Dto classes for every type of server-request which is time consuming and you have to synchronize the Dto type with your domain entity/business logic.

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  • Is EF4 "Code Only" ready for production use?

    - by Tommy Jakobsen
    I've been looking at the new Entity Framework 4 Code Only features, and I really like them. But I'm having a hard time finding good resource on the feature. Everything seems to be spread around blongs here and there, so this make me wonder if it's ready to be used for a serious project? What do you think? Is it ready for production use or should I use the more traditional approach (EDMX designer, POCO objects)? Also, I would like to know if there are any features that Code Only does not support yet, compared to the EDMX designer? What do you think about the Code Only feature? Is it "mature" yet? Thank you.

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  • import excel to sql db table

    - by droyce
    I am trying to write data from an excel spread sheet to a SQL Database. I have been able to connect to the Excel Spreadsheet and read the data but I am unable to get the data to insert into the SQL DB table. the current code is as follows any help most appreciated. Dim plmExcelCon As System.Data.OleDb.OleDbConnection Dim ldExcelDS As System.Data.DataSet Dim cmdLoadExcel As System.Data.OleDb.OleDbDataAdapter Dim PrmPathExcelFile As String PrmPathExcelFile = txtImportFileLocation.Text.ToString plmExcelCon = New System.Data.OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + PrmPathExcelFile + ";Extended Properties=Excel 12.0;") cmdLoadExcel = New System.Data.OleDb.OleDbDataAdapter("select * from [" + txtImportSheetName.Text + "$]", plmExcelCon) ldExcelDS = New System.Data.DataSet cmdLoadExcel.Fill(ldExcelDS) dgvImportData.DataSource = ldExcelDS.Tables(0) plmExcelCon.Close() cmdINSERT.Parameters("@[SQL COLUMN NAME]").Value = [Not sure how to set value from datagrid view] cnLD.Open() cmdINSERT.ExecuteNonQuery() cnLD.Close()

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